Salmonella can affect cattle in every stage of production, including pregnant cows, young calves and feedlot and adult cattle. The pattern and clinical appearance will vary with animal age, production setting and the Salmonella serotype.
There are three forms of disease caused by Salmonella - enteric, systemic and inapparent. It's the enteric form that is characterized by foul-smelling, brownish, watery diarrhea with shreds of mucous, fibrin and fresh blood.
Treatment of cattle with Salmonellosis is challenging and often only marginally successful. Successful control of a Salmonella outbreak can't be done through medication alone. It requires understanding of how the disease occurs and aggressive implementation of control strategies.
Your Veterinarian Is Key Working closely with your veterinarian is critical to controlling an outbreak as quickly as possible. Taking steps to prevent Salmonella is much more rewarding than fighting your way out of an outbreak.
Salmonella can be isolated in low percentages from a huge number of potential sources, including inapparent carrier animals (cattle, dogs, birds, people, etc.), feeds, water and other places in the environment. Salmonella is one of the few organisms that can live and multiply inside the cells of the immune system, making it especially difficult to treat or control through vaccination.
Salmonella is transmitted primarily by the fecal-oral route. This means that fecal contamination of anything that will go into the mouth - water troughs, feed bunks, hay, oral medication equipment, etc. - is a very effective means to spread Salmonella. Less frequently, aerosol transmission can also occur.
Since Salmonella is transmitted by the fecal-oral route, control and prevention strategies should center on this transmission route.
Salmonella carriers are more likely to shed the bacteria when they are stressed. Where do we congregate our stressed cattle? In calving pastures and hospital and receiving pens.
Thus, these are focal areas for our control and prevention measures. These measures will focus on three principles: reducing contamination, increasing sanitation and reducing stress.
A Hit List Of Control Strategies Here's a list of control strategies:
* Wash waterers twice daily using a dilute bleach solution, especially in high-risk areas.
* Feed hay in hayracks or bunks, not on the ground where it will become contaminated with feces. Make sure feeders aren't overfilled, resulting in spillage onto the ground.
* Fill in low spots and holes that can collect water.
* Scrape dry lot pens lightly multiple times a week to remove organic matter, promote drying and expose the bacteria to UV light from the sun.
* Do not overcrowd hospital and receiving pens.
* Segregate cattle with persistent diarrhea - do not send them back to the herd or home pen.
* Avoid using oral medications for treatment. But, if oral treatment is necessary, be very sanitary. For example, wash all treatment equipment in disinfectant between calves, change your disposable exam gloves between calves, store nose tongs and rectal thermometer probes in disinfectant between calves.
* Don't use the same loader bucket to clean pens and move feed.
* Don't step in the bunks when entering and leaving pens.
Human Risks Vaccines are available and may offer some degree of protection. But, vaccines will be insufficient if management strategies to reduce contamination, increase sanitation and reduce stress aren't implemented.
There are more than 2,300 serotypes - or servovars - of Salmonella. There's much confusion and disagreement on how these serotypes should be grouped and named. Several Salmonella have the ability to infect and cause disease in multiple species, including both cattle and man. This is a very important detail to know about Salmonella.
There are reports of people contracting Salmonella while caring for sick cattle. There are also reports of cattlemen carrying the infection home to their families.
The first step in preventing this is education of personnel about the risk of infection to themselves and their family. Advise them to consult their physician for further advice. Enforce good hygiene such as wearing disposable gloves and safety glasses, not allowing eating and drinking (or dipping) in cattle working areas, and hand washing.
A sound strategy to prevent catching Salmonellosis from cattle, along with other zoonotic diseases, is called "universal precautions." This means treating every calf as if it could potentially give you Salmonella (which is true).
One other note - are you familiar with Johne's Disease (pronounced yo-nees) in cattle? If you're a cow/calf producer, you should be. The National Cattlemen's Beef Association has an informative booklet titled "Johne's Disease: Should You Be Concerned?" Contact them (303/694-0305 or www.beef.org) to obtain a copy.
In addition, "What Do I Need to Know About Johne's Disease in Beef Cattle?" is available on the National Animal Health Monitoring System Web site. Go to (www.aphis.usda.gov/vs/ ceah/cahm, then click on Beef Cow-Calf).
Footnote: Thanks to Bob Smith, DVM, for sharing his Salmonella control strategy list.